This invention relates to expandable and expanded alkenyl aromatic polymer particles. The expandable alkenyl aromatic polymer particles are made with a specific volatile fluid blowing agent mixture of a first blowing agent of 1,1-difluoro-1-chloroethane and a second blowing agent of normal pentane, isopentane, neopentane or a mixture of two or more of these pentanes.
Alkenyl aromatic polymer particles or beads, which are expandable or expanded, are known to be highly desirable for a number of uses. One highly desirable use is protection in packaging articles for shipping. Typical materials are set forth in U.S. Pat. Nos. 3,066,382; 3,188,264; 3,251,728 and 3,933,959. Another use for the expandable alkenyl aromatic polymer particles is as molding material.
Fully halogenated chlorofluorocarbons have been identified as possibly having a negative effect on the earth's ozone layer. For this reason there is a need for decreasing and eliminating the use of such fully halogenated chlorofluorocarbons in all activities which use them, including the preparation of plastic foam products.
HCFC-142b (1,1-difluoro-1-chloroethane) has been disclosed as a possible substitute for CFC-12 (dichlorodifluoromethane) in the preparation of plastic foam products.